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June 19, 2009

Climate Change Already Underway, More To Come

by Sam Savage

The US is already experiencing extreme weather, drought and heavy rainfall as a result of human-induced climate change, and the changes are likely to continue into the future, leading climate scientists reported on Wednesday.

The report "Global Climate Change Impacts in the United States" forecasts hotter, drier conditions, resulting in "significant effects on the environment, agriculture and health" for the southwest region, according to experts from 13 US government science agencies, universities and research institutes.

Researchers analyzed nine portions of the US - Southwest, Northwest, Great Plains, Midwest, Southeast, Northeast, Alaska, U.S. islands, and coasts. The report addresses impacts including changes in rainfall patterns, drought, wildfire, Atlantic hurricanes, and effects on food production, fish stocks and other wildlife, energy, agriculture, water supplies, and coastal communities.

"This is the most thorough and up-to-date review ever assembled of climate-change impacts observed to date as well as those anticipated in the future across the United States," says Evan Mills, a scientist from Berkeley Lab who helped author the report.

But Mills said there is a solution to avoiding some of the worst impacts of human-induced climate change.

"The good news is that the harshest impacts of future climate change can be avoided if the nation takes deliberate action soon. This can be done through a balanced mix of activities to reduce greenhouse-gas emissions and adaptation to the otherwise unavoidable impacts," he said.

The 36-page report comes less than six months before the UN climate meeting in December to create a new treaty to replace the Kyoto Protocol, which is set to expire in 2012.

"Temperature rises above 2 C will be difficult for contemporary societies to cope with, and are likely to cause major societal and environmental disruptions through the rest of the century and beyond," experts wrote.

According to AFP the Intergovernmental Panel on Climate Change (IPCC) admits that this goal would require industrialized nations to cut greenhouse gas emissions by 25-40 percent from 1990 levels.

"Weaker targets for 2020 increase the risk of serious impacts, including the crossing of tipping points," according to the new report.

Michael Wehner, a climate researcher in the Scientific Computing Group of Berkeley Lab's Computational Research Division, developed a precipitation map to forecast a decrease in rainfall during springtime in California as well as summertime rains in the Pacific Northwest.

"Even in areas where precipitation is projected to increase, higher temperatures will cause greater evaporation leading to a future where drought conditions are the normal state. In the southwest United States, water resource issues will become a major issue," Wehner noted.

He also developed a graphic to depict past and future projections of the global mean surface air temperature, which is an indicator of the impacts of global climate change.

"These and similar projections reveal that actions taken today would take several decades to make any noticeable change in the rate of warming. This is one of the factors that makes climate change a difficult policy issue. There is no instant gratification," Wehner said.

The new report depicts a much more intense climate future than IPCC data, which could be because the IPCC reports are at least four or five years old and fail to take newer studies into account.